/* Accumulate in temporary */
void inner4(vec_ptr u, vec_ptr v, data_t * dest) {
    long int i;
    int length = vec_length(u);
    data_t * udata = get_vec_start(u);
    data_t * vdata = get_vec_start(v);
    data_t sum = (data_t) 0;

    for (i = 0; i < length; i+=4) {
        sum = sum + (udata[i] * vdata[i]) +
        (udata[i+1] * vdata[i+1]) +
        (udata[i+2] * vdata[i+2]) +
        (udata[i+3] * vdata[i+3]);
    }

    /* finish any remaining elements */
    for(; i < length; i++)
        sum = sum + udata[i];

    *dest = sum;
}